Detached garage, breaker panel?

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  #1  
Old 06-11-07, 08:36 AM
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Detached garage, breaker panel?

I have a detached garage about 100 feet from the house. There is a 10 gauge wire with ground buried to the garage. This wire in attached to the main breaker panel in the house on a 30AMP breaker. The wire is also grounded to the grounded bar in the house panel. I purchased a new breaker panel for the garage. The 10 gauge wire is not a three strand and only has one hot I can only activate one side of the garage panel. Question is? Any problem with charging both sides of the panel with one wire? I mean attaching the 10 gauge wire to one side, then jumping to the other side. I believe both sides would work for 120 Volt. I realize I would not have 240 Volt capabilities from this breaker box. It would give me all the breakers I need. Any Info will be appreciated. Thanks
 
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  #2  
Old 06-11-07, 08:49 AM
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No problem energizing both sides of the panel with the same hot feed. However the lugs are probably only rated for one wire. There are a number of different ways to deal with this.

You can use up to 3.6 KW of power in the garage. If the distance is long, use less than that to keep the voltage drop within reason. You're on the edge here at 100 feet. As long as you don't plan to use more than about 2 KW at one time, you should be fine.
 
  #3  
Old 06-11-07, 09:10 AM
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detached garage

Thank you very much for the reply. One other question? The ground wire on the 10 gauge feed is grounded at the house in the main panel. Then attached to the garage panel. Do I need any additional grounding? A copper rod in the ground? I think that would be double grounding? Thanks
 
  #4  
Old 06-11-07, 09:22 AM
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Yes, you need to drive a 5/8" x 8' copper-clad ground rod at the detached garage. Use an acorn clamp on the ground rod and connect it to the ground bus of the garage subpanel using bare #6 copper wire.

The ground and neutral buses in the garage subpanel should be electrically isolated.
 
  #5  
Old 06-11-07, 03:30 PM
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Detached garage

Thank you very much. Last question (I hope). What do you mean by electrically isolated? Thanks
 
  #6  
Old 06-11-07, 04:08 PM
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A subpanel must have separate neutral and ground bars, and those bars cannot connect to each other (this is different than a main panel where ground and neutral are connected). For most subpanels, this means you need to buy an add-on ground bar kit for the panel; and you must remove the bonding screw or strap from the neutral bar. The installation instructions with the panel usually indicate what to do to isolate the neutral bar. This also means that when you run new circuits into the subpanel, the white neutrals and bare grounds must land on the correct bars.
 
  #7  
Old 06-12-07, 04:56 AM
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Detached garage, breaker panel.

Thanks again, this is great information. I will obtain an add-on ground bar kit and copper-clad grounding rod. To sum it up, if Iím not mistaken. I have a 30 AMP breaker in the house main panel with a 10 gauge hot, neutral and ground going to the detached garage. In the detached garage, the 10 gauge hot will feed both sides of the bus, the white neutral and the ground from the breaker in the house will attach to the subpanels neutral bar. I will install the add-on ground bar kit and attach it to the 8í grounding rod. This will be independent from the ground and neutral from the house feed. The circuits in the garage will attach to the sub-panel: white (neutral) and black (hot) to the subpanels bars. All the grounds from the new garage circuits attach to the installed add-on ground. The ground from the 30 AMP breaker in the house, attaches to the panels neutral bar along with the whites? The grounds from the new garage circuits are separate and independent, attached to the add-on ground bar kit. I think I have it correct. The ground on the 10 gauge feed from the house goes to the sub panels neutral bar -or-would this also attach to the add-on ground in the subpanel? Thanks.
 
  #8  
Old 06-12-07, 05:03 AM
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You have a few things wrong.

At the main panel the ground and neutral wire attach wit the the other ground and neutral wires (usually the same buss bar), and the hot wire attaches to the circuit breaker.

At the sub panel, the hot wire (in your case) attaches to both lugs so that it feeds both halves of the panel. The neutral wire attaches to the neutral buss (the existing buss bar that you will not bond to the panel). The ground wire from the house and the ground rod attach to the new ground buss you will install in the panel which will bond to the panel.

Wire your circuits with the hot wire to the breaker, the white wire to the neutral buss and the ground wire to the ground buss.
 
  #9  
Old 06-12-07, 03:02 PM
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Smile Detached garage, breaker panel.

Thank you. I understand perfectly. You have been a great help.
 
  #10  
Old 06-12-07, 05:10 PM
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One thing I did not see mentioned: Since this is a detached garage, if the panel box has space for more than six breakers, there will need to be a main breaker to act as a shutoff. (Correct me if I'm wrong, but I'm thinking this is true if there is space for more than six breakers even if less than six breakers are actually installed.)

I'm thinking this would actually make the connection of the two buss bars to the single hot easier. He could install a single pole 30A breaker (back feed) in the panel as the "main", connect the single hot feed to it, then connect a #10 wire between the two lugs, thus energizing the other buss bar.

I would definately want to label the panel to clearly indicate that the panel cannot supply 230V.
 
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Old 06-12-07, 06:17 PM
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"...Correct me if I'm wrong, but I'm thinking this is true if there is space for more than six breakers even if less than six breakers are actually installed..."

Good question. Even a typical 6-space has room for 12 circuits in tandem configuration. Many of them accept tandems, IIRC.
 
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Old 07-16-07, 05:40 AM
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Smile 12 or 14 gauge? Garage wiring.

Great site / information. I have the sub-panel w/ two 8 foot 5/8 ground rods outside running # 6 solid to the neutral in the panel. I'm only running 10/2 for power. Trying to decide if I should run 12 or 14 gauge wire in a detached garage. 14 is easier to pull. Will be wiring receptacles, lights and garage door openers. Max load in the garage is 30 AMP. Thanks in advance.
 
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Old 07-16-07, 06:05 AM
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Unless I am running a circuit for a specific purpose, I make my general purpose circuits all 20 amp circuits meaning 12 gage wire. I do this because 12 gage wire is only a little more expensive but can carry one third more power.

I do not know your plans for the garage, but I would run a 15 amp circuit for the lights. I would then run a 20 amp circuit for the garage door openers. One 20 amp circuit can handle two garage door openers, unless you are talking about very large motors on those openers. I would then run one or two 20 amp circuits for the receptacles. Don't forget that the general purpose receptacles need to be GFCI protected, which you can do at the panel or at the first receptacle (using a GFCI receptacle will be cheaper than a GFCI breaker).
 
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Old 07-16-07, 06:05 AM
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Just to give yourself added capability to run a couple of tools at once I would run a 20 amp circuit on #12 wire for the receptacles and a 15 amp circuit on #14 for lighting.
 
  #15  
Old 07-16-07, 09:52 AM
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What wire are yo feeding the sub panel with. If it includes a ground wire then yo must connect yor ground rods to the ground bus not the neutral bus. The neutral bus must be separated from the ground bus when a ground wire is included in the feed to a detached building.
 
  #16  
Old 07-16-07, 12:38 PM
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Originally Posted by joed View Post
What wire are yo feeding the sub panel with. If it includes a ground wire then yo must connect yor ground rods to the ground bus not the neutral bus. The neutral bus must be separated from the ground bus when a ground wire is included in the feed to a detached building.
This is what I'm doing: At the main panel the ground and neutral wire attach with the other ground and neutral wires, and the hot wire attaches to the circuit breaker.

At the sub panel, the hot wire attaches to the in lug feeding the panel. The neutral wire attaches to the neutral buss (the existing buss bar). The ground wire from the house and the ground rod attach to a new ground buss I installed in the panel which bonds to the panel.

Circuits: the hot wire to the breaker, the white wire to the neutral buss and the ground wire to the ground buss.

Thanks
 
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Old 07-16-07, 02:04 PM
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That is good about the grounds. I mention it because in your original post you stated the ground rods were connected to the neutral bus. Neutral and ground bus must be unbonded in this sub panel.
 
  #18  
Old 08-05-07, 06:27 AM
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Hole size?

Iím going to start pulling receptacle wires in the new garage. Question is: What size hole should I bore in the vertical 2x4 studs to run the wire too and between the wall receptacles. Sounds simple, but, I donít want to damage the integrity and strength of the studs. Iím using 12-2 W/G. Thanks.
 
  #19  
Old 08-05-07, 06:42 AM
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Under 3/4" makes it hard to pull #12. 1" you can run 2 may be three but you really shouldn't bundle wires.
 
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Old 08-05-07, 07:04 AM
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1" is nice, but you need to make sure the hole is very centered in a 2x4.
Three to four 12/2 cables is absolutely fine.
For one thing this is not bundling. Second, even if it was, four two wire cables is NOT a concern with regard to derating.
Over nine "conductors" derating becomes an issue. Four 12/2's is eight "current carrying conductors".
 
  #21  
Old 09-04-07, 05:50 AM
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Talking Thanks for the help.

Just want to say my garage project went extremely well after all the help I received from this site. Everything works perfectly. I did use about 750' of #12 wire. Thanks again.
 
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